In the U.S., sexually transmitted infections (STIs) disproportionately affect adolescents, especially African Americans [CDC, STD Surveillance, 2005]. Sexual risk behaviors do not solely explain the magnitude of their increased risk [Ellen el al., 1998], leading investigators to explore other explanations such as partner selection patterns. Numerous studies have found that certain sexual partner characteristics, more broadly referred to as sexual mixing patterns, are associated with STIs, with differences by gender and ethnicity. For example, compared to their peers, African American male youth more likely to have concurrent sex partners [CDC, YRBS, 2004] and African American female youth are more likely to have partners who have been incarcerated [Mertz, 2002; Pack, 2000; Oh, 1994]. Our current understanding of the socio-cultural determinants of sex partner selection is limited. Theories of sexual partner selection that could be proposed to inform our discussion have not been developed with impoverished youth of color in mind. The goal of the proposed study is to identify factors beyond socioeconomic status and individual sexual behaviors, particularly social contexts, which contribute to high rates of STIs in African American youth. Specifically, we are interested in examining gender role beliefs and their association with sexual partner selection and risk behaviors among an urban sample of youth. Gender role beliefs are culturally-bound beliefs and expectations about men and women that dictate unique and specific gendered behaviors. Through a demographically representative sample of 15-24 year olds in Baltimore, MD, the study aims to: 1. determine if gender role beliefs (hypermasculinity, hyperfemininity, power distribution in relationships), sexual partner selection patterns, and risky sexual behaviors vary by age, gender, race/ethnicity, and SES; 2. determine whether gender role beliefs mediate the effects of race/ethnicity and SES on sexual partner selection patterns and risky sexual behaviors; and 3. qualitatively explore gender role beliefs and sexual behaviors among 15-24 year old females in Baltimore, MD. To meet the study aims, we will conduct a random-sample cross-sectional survey (N=480) and in-depth interviews (N=40) of 15-24 year olds across Baltimore City, Maryland. The study is one of the first community-based studies of gender role beliefs and partner selection patterns among an economically and racially diverse sample of male and female youth.